efficacious.
Effective; possessing efficacy.
Meaning & usage
Effective; possessing efficacy.
This medicine is efficacious.
Where this word comes from
From Old French efficacieux (whence -acious), from Latin efficāx (“efficacious”) + -ous, from efficere (“to effect, to accomplish”); see effect.
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Definitions, grammatical labels, IPA, etymology and examples: Wiktionary contributors, extracted by Kaikki / Wiktextract. Adapted under CC BY-SA 4.0. Selected fields and authored examples are shown; third-party quotations and audio are omitted. See contributor history.
Last enriched 2026-09-10. Definitions are in English. Romanizations are shown when supplied by the source; syllable estimates are omitted for unsupported scripts.